As Mariano Rivera heads off into retirement, he does so with almost every World Series record a relief pitcher can own.

But he didn’t get them all.

Former A’s reliever Darold Knowles did something 40 years ago this October that nobody — not even Rivera — ever matched. Knowles remains the only pitcher ever to appear in all seven games of a single World Series.

“It’s part of my claim to fame, which I’m very proud of,” he said.

The left-hander totaled 6¿1/3 innings in helping Oakland topple the New York Mets in 1973. He saved Games 1 and 7, allowing the Swingin’ A’s to celebrate the second of three consecutive World Series titles.

Reggie Jackson earned MVP honors by going 9 for 29 (.310) with a homer, three doubles and six RBI. Knowles, though unsung, earned his own niche by going 7 for 7 on the mound.

“I had a good series. It was kind of unusual,” Knowles, now 71, said. “I’m surprised that it hasn’t been done before or since.”

Rivera, the greatest reliever in history, never pitched more than four games in any of his seven World Series. Other relievers have appeared in as many as six games: Hugh Casey (’47), Fingers (’72 and ’73), Pedro Borbon (’72), Dan Quisenberry (’80), Tim Worrell (’02), Felix Rodriguez (’02) and Alexi Ogando (’11).

Knowles is now the pitching coach for the Dunedin Blue Jays (Class A), where the October iron man concedes he still has a hard time adjusting to the modern fears over pitch counts and workload.

He said during that ’73 World Series, he never once had a conversation with manager Dick Williams or pitching coach Wes Stock about whether he might be available.

“Years ago, we thought the more you threw, the better,” Knowles said during a reunion of the ’73 champions in Oakland earlier this season. “Obviously, it’s not that way now. You protect young pitchers. You limit their innings. You limit their times getting up and throwing.

“They watch young pitches like a hawk from the top on down. They’re all protected. It’s like they’re afraid they’re going to get tired. And if they get tired, they’re going to get hurt.”

On the other hand, Knowles dismisses the notion that his own World Series feat was Herculean. He said that pitching in all seven games was made possible by two off-days — and a few quirks of fate.

For one thing, the series needed to go the distance (that’s only happened 36 times in the best-of-seven format). For another, the flow of the game dictated whether or not he would be used.

In Game 7, for example, Knowles wound up relieving a Hall of Fame reliever — taking over for Rollie Fingers — only because Gene Tenace committed a two-out error at first base, bringing the tying run to the plate.

Fingers had already worked 3.1 innings, so Williams summoned Knowles to finish things off against Wayne Garrett for the final out. He got coaxed a pop out to shortstop Bert “Campy” Campaneris to earn the save.

“I told Dick Williams, ‘You were pretty brave to take Rollie Fingers out and put me in,'” Knowles said. “And I’m forever grateful to him. And to Gene Tenace, who booted a ball in the inning to help things along.”

Knowles, a Missouri native, pitched 16 seasons in the big leagues starting in 1965. He made the ’69 All-Star team while pitching for the Washington Senators (under manager Ted Williams) and went on to register 143 career saves.

But when Knowles overhears people saying, “Remember him?” he knows they’re talking about 1973.

Asked if he kept any souvenir from his seven-game stretch in ’73, Knowles said he was never too smart about tucking away such memorabilia. Then he suddenly recalled that he did have one keepsake.

Daniel Brown is a sports writer for the Bay Area News Group known for his award-winning profiles on subjects ranging from Jerry Rice to Sergio Romo to Taylor Swift. The Cotati native is a graduate of UC Davis.